The present invention relates to a variable valve actuating mechanism for an internal combustion engine.
Japanese Patent Application Publication No. 2002-256905 (EP 1 234 958 A2) shows an intake control apparatus for an internal combustion engine equipped with a lift and operating angle varying mechanism capable of varying an intake valve operation angle and an intake valve lift quantity simultaneously and continuously. This apparatus reduces pumping loss, and controls an intake air quantity independently of a throttle valve.
When the intake valve lift quantity varies from cylinder to cylinder of an engine because of dimensional tolerance of parts and component assemblage, the intake air quantity varies from cylinder to cylinder, and hence the output torque of the engine fluctuates. In such a state, the engine generates unpleasant vibrations and noises to a level badly affecting the quality of idling operation in which the demand for stability and silence is specifically high. As the variation in intake valve lift quantity is in the order of a few micrometers (μm)˜ a few hundreds micrometers (μm), the variation is not problematical in effect in a conventional internal combustion engine arranged to control the intake air quantity with a fixed cam and a throttle valve.
The apparatus disclosed in the above-mentioned patent document is arranged to contain the variation in the intake valve lift quantity among the cylinders within a predetermined range.